A substrate, e.g., a semiconductor wafer, is subjected to a plasma processing such as an etching process in a substrate processing apparatus. The substrate processing apparatus includes an airtightly sealed processing chamber and a mounting table arranged therein to mount a target substrate thereon. Then, a plasma is generated in the processing chamber and the plasma processing is performed by applying the generated plasma to the target substrate.
In the substrate processing apparatus, a heater for heating the substrate and an attracting electrode plate for holding the substrate, for example, are provided inside an electrostatic chuck (ESC) of the mounting table to hold the target substrate and maintain the temperature of the substrate adequate for the plasma processing.
A conventional art related to such the electrostatic chuck is disclosed in e.g., Japanese Patent Laid-open publication No. 2000-332089. The conventional art discloses an electrostatic chuck developed to obtain an easily controllable strong attractive force for holding a wafer flat, and to adequately heat the wafer without temperature irregularity. Specifically, the disclosed electrostatic chuck for heating and holding the wafer has a wafer plate including a bipolar electrostatic chuck portion for holding the wafer flat and a heating portion for heating the wafer by using an AC power supply. In the electrostatic chuck, at least one of the bipolar electrodes of the electrostatic chuck portion serves as a heater of the heating portion.
FIG. 5 is a partially enlarged cross sectional view showing an electrostatic chuck 80 according to the conventional art. In FIG. 5, the electrostatic chuck 80 includes an electrostatic chuck main body 81, a high voltage (HV) electrode plate 82 provided in the electrostatic chuck main body 81, a spiral heater 83, and DC power supplies 84 to 86 for supplying DC powers to the HV electrode plate 82 and the heater 83.
Such the electrostatic chuck 80 is manufactured by a hot press (sintering) method, for example. Specifically, inner and outer spiral resistors to be formed as the heater 83, a ceramic plate body to be formed as an intermediate layer of the electrostatic chuck 80, and the HV electrode plate 82 are coated on a ceramic plate body to be formed as a bottom surface of the electrostatic chuck main body 81.
Then, a ceramic plate body to be formed as a top surface of the electrostatic chuck 80 is stacked on the coated ceramic plate body. Thereafter, the electrostatic chuck 80 is fabricated by hot pressing the thus-provided layers of the electrostatic chuck 80.
When the layers are prepared, the sizes thereof are made to be greater than their final sizes, considering a distortion caused by the hot press. Accordingly, after such a press forming, the hot pressed body is polished into the desired size. The completed electrostatic chuck 80 is adhesively joined to a support plate 90 by using, e.g., an adhesive 87.
Since, however, the conventional electrostatic chuck employs such a spiral heater, a certain gap is required between the heater and a mounting surface of the substrate to remove the temperature irregularity caused by a heat transfer pattern from the spiral heater. Accordingly, the electrostatic chuck can not be made thin, and thus suffers from poor start-up property in heating the substrate and low response speed to temperature control.
Moreover, since the conventional electrostatic chuck is adhesively joined to such a base by using an adhesive, it is difficult to obtain a high thermal conductivity. Furthermore, due to the costly hot pressing process, the manufacturing cost of the electrostatic chuck is high and, thus, is economically unfavorable.